The overall objective of this project is to explore the capabilities of new ultrasonic techniques to non-invasively evaluate and quantitate atherosclerotic plaques and their effects on the circulation of the blood. We will utilize non-invasive, surgical and x-ray arteriographic techniques and explore the direct and indirect effects of plaquing with continuous-wave Doppler, pulsed wave Doppler, and combinations thereof with the utilization of frequency spectral analysis and will utilize high resolution B-scan ultrasonic imaging. Human subjects will be primarily utilized, but some in vitro modeling will be used.